a(n) = 8*binomial(6*n+8,n)/(6*n+8).

Terms

a(0) =1a(1) =8a(2) =76a(3) =800a(4) =8990a(5) =105672a(6) =1283464a(7) =15981504a(8) =202927725a(9) =2617624680a(10) =34206162848a(11) =451872681728